In patents and academic literature relating to data networks, there is a considerable literature on congestion control. Thousands of academic papers have been written on the subject and numerous patents have been issued. A major characteristic of network traffic is that it is bursty. However, traditional analytical techniques have been developed from telephony assume a continuous stream. Further, the mathematics of queuing theory was only tractable for Poisson distributions, so much effort was made assuming traffic was Poisson (which it isn't) or changing the traffic pattern to be Poisson so that the mathematics could be applied. None of these have led to satisfactory solutions.
Prior art suffers from two significant limitations: (1) it attempts to solve the problem by creating special cases; and/or 2) either there is a rigid mapping to mechanism (i.e. connection-like) or it is left as an exercise to the implementer to translate the desired Quality of Service (QoS) characteristics into reality. This renders it difficult to secure agreement across providers.
In general, the classes of QoS that prior art schemes recognize are based on specific current applications, e.g. voice, web, mail, and the like. This, in turn, presents at least two problems: First, each is a special case. If a new application comes along, the mechanism must be modified to accommodate it. Special cases have a tendency to proliferate. New ones are going to meet with considerable resistance. Secondly, it fails to take into account the real properties of the network. One needs an approach that is more comprehensive and less tied to the specific characteristics of current applications.
Recently, there has been much interest in the observation that traffic exhibits self-similarity. While there is not complete consensus as yet, it does appear that the self-similarity of traffic is an artifact of flow control. With large numbers of connections each with flow control responding to different points of congestion along its path and different (and varying) amounts of buffering at the ends would create such chaotic burstiness as to appear to be self-similar.
This is reinforced by observations that measures of the self-similarity of traffic indicate that TCP traffic is more strongly self-similar than UDP traffic. Since UDP has no flow, control and in fact, no mechanisms that would affect self-similarity, the source of burstiness in UDP traffic reflects the burstiness of the applications themselves. And while all applications are bursty, the nature and degree of their burstiness varies widely, which is reflected in the weaker self-similarity measures. The burstiness of applications that use TCP is more dominated by the pattern imposed by TCP flow control, which makes TCP traffic exhibit greater self-similarity.
However, this avenue of work appears to have primarily descriptive, not prescriptive value. It does not teach what should be done to take advantage of this property to avoid congestion or meet QoS requirements. In fact, it is somewhat fatalistic in that it says that no matter what is done, the traffic will always look the same. So one might conclude that there is nothing to be done. Alternatively, it can also be interpreted as saying that Internet traffic is chaotic.
It would be desirable to provide methods, systems and devices that exploit the nature of network traffic to provide congestion control.